Familiarity:
I've used it once or twice and have initial impressions

All I am going to say is buy em, they are totally worth it. Like everyone said size down. I went with my normal size and they are a little big, but my size was not in stock, they moved around and shifted a little while riding but never came off my knee. I rode with them on for 5 miles uphill and they are pretty breathable, and I really like that. When I reached the DH I took a small fall and they did shift off my knee a little bit but took the brunt of them impact, fully impressed, and can't wait till my size is in stock.